https://issues.apache.org/jira/browse/CB-9407
For some reason permission is an empty array
config.doc.findall('permission');
https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/metadata/firefoxos_parser.js#L134
although the permission exists in ``this.config_path``
<permission description="Required for accessing cameras on the device."
name="camera" privileged="true" />
<permission name="systemXHR" privileged="true" />
